Vapor electric rectifying system



July 27, 1937. E 2,088,436

VAPOR-ELECTRIC RECTIFYlNG SYSTEM Filed May 19, 1951 Inventor: Eugene H. Reid,

His Attorney.

Patented July 2?, i937 l"?- ELESTRIC RECTXFYING SYSTEM Eugene H. Reid, Schenectady, N. Y., assignor Electric Company, a corporat n oi Ne York Application May 19, 1931, Serial No. 538,562

ll Claims. (Cl. l'Z 5-363) My invention relates to vapor el ctric rectlfyvapor electric apparatus provided with conducing systems and iiarticularly to such systive anode shields or grids on whicla negative terns provided with means for suppressing repotential will be impressed upon the occurrence verse within the vapor electric apparatus. of a reverse arc and in which the direct current 5 It i" a well known fact that vapor electric load circuit will he simultaneously interrupted. apparatus, operation; are subject to reverse In accordance with one embodiment of my arcs which may he occasioned. by any of a numinvention, a vapor electric rec tying apparatus ber of disturbing operating conditions. In case is provided with conductive anode shields upon the vapor electric apparatus is supplying a load which are impressed normally a positive potencircuit which does not have an independent ial to maintain the apparatus in a conductive 10 counter-electromotive force, the reverse arcs 'tate. A substantially higher negative potential within the apparatus are limited to arcs between s also connected to these grids through a northe several anodes of the apparatus, but if the mally non-conductive electric valve. The grid of load circuit develops a counter-electromotive the electric valve is so connected to the system as force, such, for example, as that generated by to be responsive to transients due to the occur 15 a direct current motor, the reverse arcs within rence of a reverse are in the apparatus. For the vapor electric apparatus may form either example, upon theoccurrence of a reverse arc, between the anodes of apparatus or between it has been discovered that the metal container the cathode acting an anode and a negative or tank of a vapor electric apparatus provided anode acting as a cathode. Such reverse arcs With an insulated cathode changes its potential 20 within vapor electric apparatus, if allowed to With respect to a reference point of said appapersist, may cause serious damage not only to ratus, such as the cathode, so that it becomes the apparatus itself but to the system and other negative with respect to its cathode, while under apparatus with which the vapor electric appanormal operating conditions it is positive with ratus is associater. Heretcfore, there have been p t to i s ca h d T v l f p l i y 25 proposed certain arrangements which have had may be used to excite the grid of the aboveas their object the elimination or suppression of mentioned electric valve. In accordance with a reverse arcs vapor electric rectifiers. These modification of my invention, the grid of the arrangements of the prior art, however, have above-mentioned electric valve may be excited left Something to he desired in the way of cerfrom a current transformer responsive to surges 30 tainty and rapidity of action. in the direct current circuit of the system. In

It is an object of my invention, therefore, to still another modification of my invention, a provide an improved vapor electric rectifying ative pot is app d to the grids of e system in which a reverse are occurring in the Vapor electric apparatus by means of a mercury 5 apparatus will be suppressed with a maximum of switch. mechanically interlocked with a high 3 certainty and rapidity. speed circuit breaker in the direct current cir- It is another object of my invention to pro- Cu o t e Syst vide an improved vapor electric rectifying sys- Fora better understanding of my invention,

t i hi h the anodes of the vapor electric together with other and further objects thereof,

apparatus are surrounded with conductive reference is had to the following description 40 shields or grids on which a negative potential is taken in connection with the accompa impressed upon the occurrence of a reverse are drawing and its scop W be pointed u n e in the apparatus. appended claims. l of the accompanying It is a further object of my invention to prodrawing illustrates one embodiment of my invide an improved vapor electric rectifying sys- Vention in which a reversal of tank to cathode 45 tem including a vapor electric apparatus propotential is utilized to suppress a reverse arc in vided with conductive anode shields or grids on a vapor electric apparatus; Fig. 2 illustrates an which a negative potential will be impressed appli ati n of my inv n i n to a ys m in which substantially simultaneously with the occurrence t e ave ag V a Of t e d ect CuIleht circuit of a reverse arc in the apparatus and without may be varied by shifting the phase of an alter- 50 the aid of moving parts contacts. hating potential applied to the grids of the vapor It is a still further object of my invention to electric apparatus and in which the application provide an improved vapor electric rectifying of a negative potential to these grids is effected system including a direct current load having an in response to current surges in the direct our-- independent counter-electromotive force and a rent circuit, while Fig. 3 shows a simplified form 55 of my invention which may be suitable in cer tain instances and in which the use of an auxiliary electric valve is eliminated.

Referring now to Fig. l, I have illustrated a vapor electric rectifying system for transmitting energy from an alternating current supply circult It to a direct current load device illustrated as a motor N. This system includes a transformer 12, a vapor electric rectifying apparatus l3, and a high speed direct current circuit breaker M, which may be of any of the several types well known in the art, although I prefer to use circuit breakers of the type disclosed and claimed in United States Letters Patent l lo. 1,560,440, granted November 2, 1925 on the ap plication of J. F. Tritle. The vapor electric rec-- tifying apparatus i3, examples of which are well known in the art, comprises a metal tank or other conductive container l5, an insulated iner cury pool cathode It, a pair of anodes H and a pair of conducting shields or grids i8 surrounding the anodes ll and insulated therefrom. While I have illustrated a two-anode vapor-electrio apparatus, it will be apparent that my invention is equally applicable to such apparatus having a larger number of anodes, as would be; used in polyphase rectifying systems. In order to keep the vapor-electric apparatus I3 in a normally conductive state, the grids l8 are connected to the tank 15 through grid resistors It, a positive bias battery 20, a resistor 2| and a relay or signal device 22. The grids it are also connected to the metal tank i5 through grid resistors l9, a negative bias battery 23, which is preferably of a considerably higher voltage than the battery 2%, and a normally nonconduc tive electric valve 24. The valve 24 is provided with an anode, a cathode and a control grid and may be of any of the several types well known in the art, although I prefer to use a valve of the vapor electric discharge type. If the cathode of the apparatus I3 is chosen as the reference point of the apparatus the grid of the valve 26 is connected to the cathode l6 through a high resistance 25 and may be connected to its oathode through a capacitor 26 and a parallel connected grid leak 21. In certain cases it may be desirable to return the apparatus to an operative condition after a predetermined interval during which the disturbing conditions will have had time to disappear. This result may be accomplished by inserting in the valve circuit the contacts and operating coil of a time delay opening relay 28.

The general principles of operation of the full Wave rectifying system comprising the transformer i 2, the vapor electric apparatus 13, and the direct current load device II will be well understood by those skilled in the art, so that a detailed explanation is not deemed necessary. Under normal operating conditions the grids It will be positive with respect to the tank I5 by the voltage of the bias battery 20, while the tank I5 is normally slightly positive with respect to the cathode l6. Under these conditions the apparatus Z 3 is completely conductive and the grids I8 are ineffective. It will be assumed that the circuit breaker I4 is closed and that energy is being supplied to the motor Ii. Upon the occurrence of a reverse are, that is, in case one of the anodes ll acts as a cathode, a short circuit will be placed upon the transformer i2 during the half cycle that the faulty anode is negative with respect to the other anode and during the same half cycle the counter-electrornotive force of the load device I! will tend to send reverse power through the rectifying apparatus. The flow of reverse power occasioned by the reverse arc causes the circuit breaker I i to open and thus interrupt the flow of reverse power, but this does not remove the short circuit from the transformer i2. However, it has been discovered that the occurrence oi such an are back causes the potential of the tank iii to reverse polarity with respect to the cathode it substantially instantaneously so that the tank becomes negative with respect to the cathode. i the cathode is not taken as the reference point of the apparatus but some other point such as ground or some conductor of which the absolute potential remains substantially constant under all conditions is utilized, the change in the potential be tween the tank or a conductive member in contact with the vapor therein is utilized to actuate the valve cathode and control electrode or grid connections will be obvious to those skilled in the art. W. h the connections as described above, this results in placing a positive potential upon the grid of electric valve it to render it conducting, thus connecting the grids it to the tank it through the grid resistors ii), the negative bias battery 23 and electric valve Under this condition the are back will persist only for the remainder of the particular half cycle and thereafter the negative potential on the grids it prevents a discharge from starting from the positive anode ill to the negative faulty anode When the valve M becomes conductive, it will be noted that the alarm device or relay 2?! is energized from the batteries Elli and 23 in series through current limiting resistor 2i and electric valve 2t. As long as electric valve 26 is conducting current, the vapor electric apparatus i3 is main tained in an inoperative condition. In some 111-- stances, however, it may be desirable to restart the operation of the vapor electric apparatus after a time interval suflicient to allow the disturbing conditions to disappear. This is complishecl by means of the time delay opening relay 28, the operating coil and contacts of which are connected in series with electric valve 24. After a predetermined time interval, this relay opens its contacts, thus interrupting the current through the valve E i and allowing the positive bias battery to regain control of the grids l8 and render the apparatus fully conductive. In order to prevent operation of the apparatus, upon the occurrence of extremely short transients, the condenser 26 may be connected between the grid and cathode of the valve 24 to absorb these short transients. In such case a grid leak 2"! is preferably provided to allow the charge to leak off the condenser In Fig. 2, there is illustrated an application of my invention to a vapor electric rectifying system in which the average voltage of the direct current circuit may be controlled by impressing upon the grids it an alternating potential vari able in phase with respect to the potential of the anodes ll. In this arrangement the grids 28 are connected to the cathode through opposite halves of the secondary winding of a grid transformer 3i] and a current-limiting resistor 35, while the primary winding of the grid transformer til may be energized from any suitable source of alternating potential synchronized with that of the circuit Hi and variable in phase with respect thereto. I have shown by way of ex ample an impedance phase shifting circuit such The necessary changes in the a as that described and claimed in United States Letters Patent No. 1,719,366, granted July 9, 1929, upon the application of E. F. W. Alexanderson. In the arrangement of Fig. 2, the operation of the arc suppressing means is also modified to be responsive to current surges in the direct current circuit. is accomplished by connecting the electrical midpoint of the secondary winding of grid transformer til through the negative bias battery and the vapor electric valve 24 to the cathode it of the rectifier is. The grid of the valve 26 is energized from the secondary winding of a current transformer 33 connected in the direct current circuit. The operation of the rectifying system controlled by the variable phase grid potential will be Well understood by those skilled in the art or may be found explained in detail in United States Letters Patent No. 1,654,- 949, granted January 3, 1928, upon the application of P. M. G. Toulon. As in the arrangement shown in Fig. i, in case of a reverse are between the anodes ll, the circuit breaker it will disconnect the direct current circuit and a current surge will occur in the direct current circuit which will induce a potential in the secondary winding of the transformer 33. This transient potential is impressed upon the grid of the valve 24 to render it conductive, thus connecting the negative bias battery 23 between the cathode l6 and the control grids M3. The reverse arc will then persist only for the remainder of the particular half cycle and will be prevented from restarting, as in the arrangement of Fig. 1.

In Fig. 3 is shown a simplification of the arrangement illustrated in Fig. l in which the grids it are connected to the cathode of the rectifier apparatus i3, rather than the tank [5, through current-limiting resistors it, a current-limiting resistor 2i, and the positive bias battery 20, respectively. A mercury contact switch 34 is mechanically interlocked with the direct current circuit breaker it so as to impress the negative bias potential of the battery '23 upon the grids l8 when the circuit breaker it opens in response to reverse current due to a reverse arc in the rec tifier apparatus.

While I have described what I at present consider the preferred embodiments of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention and I therefore aim. in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In combination with a vapor electric converter comprising a cathode, a plurality of anodes and associated control grids, a circuit connecting said grids with a point on said converter normally substantially at cathode potential and including a source of rid potential for normally rendering said converter conductive, and means for suppressing an are between said anodes comprising a second circuit connecting said grids and said point and including a source of negative bias potential and a normally nonconductive electric valve, and means responsive to a change of potential of said point with respect to said cathode for rendering said valve conductive.

2. In combination. with a vapor electric converter comprising a conductive container, an insulated cathode, a plurality of anodes and associated control grids, means for suppressing an arc between said anodes comprising means responsive to a reversal of the potential between said cathode and said container for impressing upon said grids a negative bias potential.

3. In combination with a vapor electric converter comprising a conductive container, an insulated cathode, a plurality of anodes and associated control grids, means for suppressing an arc between said anodes comprising a circuit connecting said grids and said container and in-- cluding a source of negative bias potential and a normally non-conductive electric valve, and means responsive to a reversal of the potential between said cathode and said container for rendering said valve conductive.

i. In combination with a vapor electric converter comprising a conductive container, an insulated cathode, a plurality of anodes and associated control grids, means for suppressing an are between said anodes comprising a circuit connecting said grids and said container and including a source of negative bias potential and an electric valve provided with a control grid, and a connection from said valve grid to the cathode of said converter.

5. In combination with a vapor electric converter comprising a conductive container, an insulated cathode, a plurality of anodes and associated control grids, means for suppressing an are between said anodes comprising a circuit connecting said grids with a point of said converter normally substantially at cathode potential and including a source of negative bias potential and a normally non-conductive electric valve provided with an anode, a cathode, and a control grid, means for impressing upon said valve grid a potential transient occasioned by said arc, and a condenser connected between the cathode and grid of said valve to absorb smaller transient potentials occasioned by minor disturbances.

6. In combination, with a vapor electric converter comprising an insulated cathode, a plurality of anodes and associated control grids, means for suppressing an are between said anodes comprising a circuit connecting said grids with a point of said converter normally substantially at cathode potential and including a source of negative bias potential and a normally non-conductive electric valve, means responsive to a change in potential of said point with respect to said cathode for rendering said valve conductive, and a time delay relay having an operating coil and a pair of normally closed contacts serially connected in said circuit to restore said converter to normal operating conditions after a predetermined interval.

7. In a vapor electric rectifying system, the combination of an alternating current supply circuit, a direct current load circuit, a vapor electric converter comprising a conductive container, an insulated cathode, and a plurality of anodes and associated control grids, a circuit connecting said grids and said container and including a source of positive bias potential, means for suppressing an are between said anodes comprising a second circuit connecting said grids and said container and including a source of negative bias potential and a normally nonconductive electric valve provided with an anode, a cathode, and a control grid, a connection from said valve grid to the cathode of said converter, a condenser connected between the grid and cathode of said valve, a time delay relay having an operating coil and a pair of normally closed contacts serially connected in said circuit to restore said converter to normal operating conditions after a predetermined interval, and means for suppressing a reverse are between the oathode and anodes of said converter comprising means responsive to a reverse are for disconnecting said load circuit.

8. In a vapor electric rectifying system, the combination of an alternating current supply circuit, a direct current load circuit, a. vapor electric converter comprising a cathode, a plurality oi anodes and associated control grids, and means for suppressing an are between said anodes comprising a circuit connecting said grids with a point of said converter substantially at cathode potential and including a source of nega tive bias potential and a normally non-conductive electric valve, and means responsive to a predetermined rate of change of current in said direct current circuit for rendering said valve conductive.

9. In a vapor electric rectifying system, the combination of an alternating current supply circuit, a direct current load circuit, a vapor electric converter comprising a cathode, a plurality of anodes and associated control grids, and

means for suppressing an arc between said anodes comprising a circuit connecting said grids with a point of said converter substantially at cathode potential and including a source of negative bias potential and a normally non-conductive electric valve provided with an anode, a cathode, and a control grid, a series transformer in said direct current circuit, and a circuit for energizing said valvegrid from said series transformer.

10. In combination with a vapor electric converting apparatus comprising an anode, a cathode, and a conductive member in contact with the ionized vapor of the apparatus, means responsive to a reversal of the potential between said conductive member and said cathode for controlling the operation of said apparatus.

11. In combination with a vapor electric converting apparatus comprising an anode, a cathode, and a conductive member in contact with the ionized vapor of the apparatus, a device for indicating abnormal conditions of said converter, and means responsive to a reversal of the potential between said conductive member and said cathode for operating said indicating device.

EUGENE H. REID. 

